Flood Protection

Within the City of Chilliwack, there are floodplain areas for both the Fraser River and Vedder River. Portions of Greendale and Yarrow lie within the floodplain for both rivers.

The flood risk associated with these two river systems is different, and therefore the City has separate Flood Response Plans to manage the risks.  This webpage contains general information regarding flood protection and emergency preparedness for residents.  For more specific information regarding the Fraser River or Vedder River, please visit these webpages:

Flood Hazard - What Does it Mean?

Flood hazard is often expressed in terms of the likelihood or probability of a given flood event occurring. For example, the 1894 flood on the Fraser River is the largest flood on record, and is estimated to be a "1 in 500 year" event. The provincial dike standard and floodplain mapping for the Fraser River is based on this event.

The expression "1 in 500" does not mean that this size of flood will only happen once every 500 years.  For example, we can't say that because it happened in 1894, it won't happen again until close to the year 2400.   Rather, it means that there is a 1 in 500 chance of it occurring in any given year (1/500 = 0.2% chance per year).

Similarly, the provincial dike standard and floodplain mapping for the Vedder River is based on the "1 in 200 year" event. This means that there is a 1/200 (0.5%) chance of it occurring in any given year.

This explains why we can hear about large flood events, for example "1 in 100 year" flood events, happening two years in a row; the "1 in 100 year" events have a 1/100 (1%) chance of happening in any given year.

General Flood Hazard Management:

Flood hazard management is accomplished through a variety of measures, including:

• Flood Protection Infrastructure
• Emergency Dike Upgrades Plan (identifies how to address priority areas for upgrading under emergency situations)
• Flood Response Plans for the Fraser River and Vedder River
• Flood construction levels and setbacks as specified in the Floodplain Regulation Bylaw

 River Forecast Centre:

The Provincial River Forecast Centre collects and interprets snow, meteorological and streamflow data to provide warnings and forecasts of stream and lake runoff conditions around the province. Visit http://www.env.gov.bc.ca/rfc/ for current reports.

The City of Chilliwack uses the information provided by the River Forecast Centre when carrying out flood response activities.

 Flood and Emergency Information for Residents:

Download and print an Emergency Preparedness basic kit checklist (Grab & Go Kit). There are a number of resources that you can access to be prepared in the event of a flood.

The following government websites provide information on flood and emergency preparedness: www.getprepared.gc.ca, PreparedBC, www.chilliwack.com/ep and www.fraserhealth.ca

Additional Information for the Agricultural Sector:

The following websites provide information on flood and emergency preparedness for the agricultural sector:

• Farm Flood Response Toolkit available through the BC Agriculture & Food Climate Action Initiative
• Ministry of Agriculture (http://www.gov.bc.ca/al or 1-888-221-7141) 

 City of Chilliwack Floodplain/Elevation Maps:

Do you live in the floodplain? Check this map to find out.	What elevation is your home at? Check this map to find out.
Download Chilliwack Floodplain Map in PDF format with Road Names or without Road Names Updated version as of May 3, 2007 The floodplain is accurately shown on this map as based on the 2007 update. When the next mapping update is completed, it is not expected to significantly change the extent of the floodplain.	Download Chilliwack Elevation Map in PDF format (8.77 MB)